ELE4120 Bioinformatics. Tutorial 5

Transcription

1 ELE4120 Bioinformatics Tutorial 5 1

2 1. Database Content GenBank RefSeq TPA UniProt 2. Database Searches 2

3 Databases A common situation for alignment is to search through a database to retrieve the similar sequences. Common Databases: GenBank at the National Center for Biological Information(NCBI) RefSeq at NCBI TPA at NCBI UniProt 3

4 NCBI ( Established in 1988 as a National resource for molecular biology information, NCBI creates public databases, conducts research in computational biology, develops software tools for analyzing genome data, and disseminates biomedical information - all for the better understanding of molecular processes affecting human health and diseases. 4

5 5

6 ------What is GenBank: 1.1 GenBank ( GenBank is the NIH genetic sequence database, with more than 20 millions sequences for now. 6

7 The complete release notes for the current version of GenBank are available on the NCBI ftp site. A new release is made every two months. GenBank is part of the International Nucleotide Sequence Database Collaboration, which comprises the DNA DataBank of Japan (DDBJ), the European Molecular Biology Laboratory (EMBL), and GenBank at NCBI. These three organizations exchange data on a daily basis Submissions to GenBank The WWW-based submission tool, called BankIt, for convenient and quick submission of sequence data. Sequin, NCBI's stand-alone submission software for 7

8 MAC, PC, and UNIX platforms, is available by FTP. When using Sequin, the output files for direct submission should be sent to GenBank by electronic mail Access to GenBank ( GenBank is available for searching at NCBI via several methods. Text and Similarity Searching Information about Access to GenBank 8

9 9

10 1.2 The Reference Sequence (RefSeq) ( Refseq collection aims to provide a comprehensive, integrated, non-redundant set of sequences, including genomic DNA, transcript (RNA), and protein products. RefSeq is a baseline for medical, functional, and diversity studies; they provide a stable reference for genome annotation, gene identification and characterization, mutation and polymorphism analysis, expression studies, and comparative analyses. 10

11 11

12 12

13 1.3 Third Party Annotation Sequence Database ( TPA: A database designed to capture experimental or inferential results that support submitter-provided annotation for sequence data that the submitter did not directly determine but derived from GenBank primary data. TPA records are divided into two categories: TPA:experimental: Annotation of sequence data is supported by peer-reviewed wet-lab experimental evidence. TPA:inferential: Annotation of sequence data by inference (where the source 13

14 molecule or its product(s) have not been the subject of direct experimentation). 14

15 1.4 UniProt UniProt (Universal Protein Resource) is the world's most comprehensive catalog of information on proteins. It is a central repository of protein sequence and function created by joining the information contained in Swiss-Prot, TrEMBL, and PIR. UniProt has three parts, each optimized for different uses. The UniProt Knowledgebase (UniProtKB) is the central access point for extensive curated protein information, including function, classification, and cross-reference. The UniProt Reference Clusters (UniRef) databases combine closely related sequences into a single record to speed searches. The UniProt Archive (UniParc) is a comprehensive repository, reflecting the history of all protein sequences. 15

16 16

17 17

18 2. Database Searches GenBank database with more than 20 millions sequences at NCBI Compare a new found gene with similar sequences in database might give us an idea about the new found gene 18

19 Searching sequences that align well with our sequence by calculating its alignment with each sequence in database needs long execution time Many database search algorithm are used instead of alignment scores BLAST, FASTA Fast Not guaranteed to be best match, but with high probability that the return sequences are well aligned with our query sequence 19

20 BLAST algorithm Basic Local Alignment Search Tool Original BLAST searches a sequence from the database for maximal ungapped local alignments For protein or nucleotide sequences Many members of the BLAST family E.g. BLASTP, BLASTN, BLASTX 20

21 21